1: With 1-hydroxy-pyrrolidine-2,5-dione; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride in N,N-dimethyl-formamide T=0 - 20°C; 3 h; 2: With ammonia in water; N,N-dimethyl-formamide T=0 - 20°C; 0.5 h;